Baseline 6-min walk distance predicts survival in lung transplant candidates

In a large, prospectively followed, two-center cohort of patients listed for lung transplantation (n = 376), we used Cox proportional hazards models to determine the importance of baseline 6-min walk distance (6MWD) in predicting patient survival. 6MWD used as a continuous variable was a significant predictor of survival after adjusting for other important covariates when transplant was considered as a time-varying covariate (HR for each 500 ft increase in 6MWD = 0.57, 95% CI: 0.43-0.77, p = 0.0002). 6MWD remained an important predictor of survival in models that considered only survival to transplant (HR for each 500 ft increase in 6MWD = 0.41, 95% CI: 0.27-0.62, p < 0.0001) or survival only after transplant (HR for each 500 ft increase in 6MWD = 0.40, 95% CI: 0.22-0.72, p = 0.002). Unadjusted Kaplan-Meier analysis demonstrates significantly different survival by 6MWD tertiles (< 900, 900-1200, or > 1200 ft, p-value = 0.0001). In the overall model, 6MWD prediction of survival was relatively homogeneous across disease category (6MWD by disease interaction term, p-value = 0.63). Our results demonstrate a significant relationship between baseline 6MWD and survival among patients listed for lung transplantation that exists across all native disease categories and extends through transplantation. The 6MWD is thus a useful measure of both urgency and utility among patients awaiting lung transplantation.